planetstack/observer/syncstep.py

   1 import os
   2 import base64
   3 from datetime import datetime
   4 from planetstack.config import Config
   5
   6 class FailedDependency(Exception):
   7     pass
   8
   9 class SyncStep:
  10     """ A PlanetStack Sync step.
  11
  12     Attributes:
  13         psmodel        Model name the step synchronizes
  14         dependencies    list of names of models that must be synchronized first if the current model depends on them
  15     """
  16     slow=False
  17     def get_prop(prop):
  18         try:
  19             sync_config_dir = Config().sync_config_dir
  20         except:
  21             sync_config_dir = '/etc/planetstack/sync'
  22         prop_config_path = '/'.join(sync_config_dir,self.name,prop)
  23         return open(prop_config_path).read().rstrip()
  24
  25     def __init__(self, **args):
  26         """Initialize a sync step
  27            Keyword arguments:
  28                    name -- Name of the step
  29                 provides -- PlanetStack models sync'd by this step
  30         """
  31         dependencies = []
  32         self.driver = args.get('driver')
  33         try:
  34             self.soft_deadline = int(self.get_prop('soft_deadline_seconds'))
  35         except:
  36             self.soft_deadline = 5 # 5 seconds
  37
  38         return
  39
  40     def fetch_pending(self):
  41         return []
  42         #return Sliver.objects.filter(ip=None)
  43
  44     def check_dependencies(self, obj, failed):
  45         for dep in self.dependencies:
  46             peer_object = getattr(obj, dep.lower())
  47             if (peer_object.pk==failed.pk):
  48                 raise DependencyFailed
  49
  50     def call(self, failed=[]):
  51         pending = self.fetch_pending()
  52         for o in pending:
  53             try:
  54                 for f in failed:
  55                     self.check_dependencies(o,f) # Raises exception if failed
  56                 self.sync_record(o)
  57                 o.enacted = datetime.now() # Is this the same timezone? XXX
  58                 o.save(update_fields=['enacted'])
  59             except:
  60                 failed.append(o)
  61
  62         return failed
  63
  64     def __call__(self, **args):
  65         return self.call(**args)